Bernie Masters is a geologist/zoologist who spent 8 years as a member of the Western Australian Parliament. Married to Carolina since 1976 and living in south west WA, Bernie is involved in many community groups. This blog offers insights into politics, the environment and other issues that annoy or interest him. For something completely different, visit www.fiatechnology.com.au for information about vegetated floating islands - the natural way to improve water quality.

Saturday, January 19, 2013

BLACK CARBON - A FAR MORE POWERFUL SOURCE OF GLOBAL WARMING THAN THOUGHT BY THE IPCC

For many years, I have accepted that the climate of our planet has been changing, with global warming the most obvious symptom. But I've been highly dubious of the claim by what are called 'climate change alarmists' that the problem is almost totally due to our burning of fossil fuels and the resulting carbon dioxide emitted into the atmosphere.

Shown below are the results of new research which shows that black carbon - soot - has a much greater influence on climate change than claimed by the IPCC and 'alarmists'. Reduction of soot emissions to the atmosphere will also bring major improvements to the air quality of billions of people in developing countries, lowering their death rates and improving their quality of life. Please read on.....

From: Yale Environmental 360

17 Jan 2013: Analysis

Black Carbon and Warming:
It’s Worse than We Thought

A new study indicates soot, known as black carbon, plays a
far greater role in global warming than previously believed and is second only
to CO2 in the amount of heat it traps in the atmosphere. Reducing some forms of
soot emissions — such as from diesel fuel and coal burning — could prove
effective in slowing down the planet’s warming.

by Carl Zimmer

It rises from the chimneys of mansions and from simple hut stoves. It rises
from forest fires and the tail pipes of diesel-fueled trucks rolling down the
highway, and from brick kilns and ocean liners and gas flares. Every day, from
every occupied continent, a curtain of soot rises into the sky.

What soot does once it reaches the atmosphere has long been a hard question to
answer. It’s not that scientists don’t know anything about the physics and
chemistry of atmospheric soot. Just the opposite: it does so many things that
it’s hard to know what they add up to.

To get a clear sense of soot — which is known to scientists as black carbon —
an international team of 31 atmospheric scientists has worked for the past four
years to analyze all the data they could. This week, they published a 232-page report in the Journal of Geophysical Research.
“It’s an important assessment of where we stand now,” says Veerabhadran Ramanathan
of the Scripps Institution for Oceanography, an expert on atmospheric chemistry
who was not involved in the study.

The big result that jumps off the page is that black carbon plays a much bigger
role in global warming than many scientists previously thought. According to
the new analysis, it is second only to carbon dioxide in the amount of heat it
traps in the atmosphere. The new estimate of black carbon’s heat-trapping power
is about twice that made by the Intergovernmental Panel on Climate Change in
2007.

This result suggests that cutting black carbon emissions could go a long way to
slowing climate change. But the authors of the new study warn that we’ll need
to be careful about the sort of black carbon we choose to cut. “There’s a
significant potential, but you have to be very targeted,” said co-author Sarah Doherty
of the University of Washington.

Soot is made up of tiny dark particles. When it rises from fires, it mixes with
dust, sulphates, and other material rising from the ground. As it ascends
through the atmosphere, it can drift into clouds, mixing with the water
droplets. Rain and snow then wash out the black carbon particles and bring them
back to Earth.

Along the way, black carbon exerts all sorts of influences, some of which help
warm the atmosphere and some of which cool it. When sunlight strikes black
carbon, its dark hue causes it to heat up, something like the way a black tar
roof gets hot on a sunny day. When black carbon falls on ice and snow, it
smudges their bright white reflective surfaces. As a result, less sunlight
bounces back out to space, leading to more warming.

In clouds, black carbon has a dazzling number of effects. “The more we study
it, the more mechanisms people find,” says Doherty.

If black carbon heats up the layer of the atmosphere where clouds are forming,
for example, they will evaporate. They can no longer reflect sunlight back into
space, and so the soot-laced clouds end up warming the atmosphere. But black
carbon that hangs above low-lying stratocumulus clouds has a different effect.
It stabilizes the layer of air on top of the clouds, promoting their growth. It
just so happens that thick stratocumulus clouds are like shields, blocking
incoming sunlight. As a result, black carbon also ends up cooling the planet.

All these effects depend, ultimately, on how much soot is in the air, which, in
turn, depends on the many different kinds of sources of soot all over the
world. Estimating that flux is a major challenge, and so it’s not too
surprising that different teams of scientists have ended up with markedly different
estimates for the net effect of soot on the climate.

In 2009, Doherty and her colleagues set out to make careful estimates of all
sources of black carbon, using data from monitoring stations around the world.
They then ran computer models of the atmosphere to measure the effects of the
black carbon, based on what scientists have learned about chemical reactions in
clouds from experiments and observations. Along with the effect that soot had
on clouds, the scientists also estimated the total amount of warming that
occurred as the soot directly absorbed sunlight, and as it darkened snow and
ice.

After the scientists had taken into account all of these effects, they tallied
them up to calculate how much extra energy was being stored in the atmosphere
thanks to black carbon. Climate scientists typically express that energy as
watts per square meter of the Earth’s surface. The number they got — 1.1 watts
— was enormous. Carbon dioxide, the biggest heat-trapper in the atmosphere, is
responsible for an estimated 1.56 watts per square meter. Black carbon takes
second place. “It took a while to convince ourselves it was correct,” says
Doherty.

If black carbon is responsible for trapping so much heat, then reducing soot
may be an effective way to slow down the planet’s warming. It’s even more
attractive because black carbon washes quickly out of the atmosphere, and so
reducing soot emissions would lead to a fast fall in the concentration of black
carbon in the atmosphere. Carbon dioxide, by contrast, lingers for centuries in
the atmosphere.

James Hansen of the Goddard Institute for Space Studies has been arguing for
such a strategy for over a decade. But the new study reveals a paradox in
reducing soot to fight global warming. If tomorrow we could shut down every
brick kiln, every burning farm field, and every other source of soot, we would,
on balance, have no effect on global warming whatsoever.

How can this be? Because when things burn, black carbon is not the only thing
they produce. A forest fire produces black carbon as well as organic carbon
molecules. The forest fire black carbon helps to warm the planet, but the
organic carbon creates a haze that blocks sunlight, cooling the atmosphere. The
two emissions cancel each other out. “In the real world you can’t just get rid
of black carbon emissions,” says Doherty. “You get rid of other things as
well.”

But Doherty and her colleagues found that some sources of soot — including coal
and diesel fuel — produce a lot of warming with very little compensating
cooling. They suggest that these sources should be the top priority for efforts
to fight global warming.

Diesel fuel looks to be an especially ripe target. “That message is loud and
clear,” says Ramanathan. Making diesel an even more attractive candidate for
attack is the fact that reducing much of its black carbon emissions might simply
be a matter of upgrading old, soot-spewing engines with newer technology.
Developing countries, in particular, could put in place regulations about
burning diesel to upgrade their rapidly growing auto fleets.

Coal is another potent source of warming from soot, the scientists found,
whether burned industrially or at home. So are the small stoves that billions
of people use to cook. Fueled by wood or coal, they spew billows of sooty
smoke. Engineers in recent years have designed efficient, cheap stoves that release
much less black carbon. Getting those stoves into people’s homes
would take a lot of warming soot out of the atmosphere.

Doherty does not see her new study as the end of the story. While she and her
colleagues conclude that soot most likely produces 1.1 watts per square meter,
they still put a margin of error on their results. They calculate that there’s
a 90 percent chance the actual figure falls between .17 and 2.1 watts. To
tighten that range, they still need to better understand the many ways that
soot alters clouds, and also get a better fix on the amount of soot each source
produces. “We need to dig deeper on that,” she says.

Nevertheless,
Doherty and her colleagues see many good reasons not to wait for a more precise
understanding of soot before taking steps to reduce it. Along with its effect
on the global climate, a number of studies also indicate it has powerful
influences on some regions of the planet. A lot of soot falls onto the glaciers
of Himalayas, for example, speeding up their melting.
Millions of people depend on that ice for their water supply. Soot also has a
particularly large effect on the circulation of the atmosphere around India,
which ultimately reduces the amount of rainfall produced by monsoons.

Even before soot gets far into the air, it has a particularly harmful effect:
it makes people sick. In recent days, news reports from China have provided
startling images of Beijing swaddled in a blanket of sooty smog. That air
pollution, from cars and coal-fired plants, takes a terrible toll on the
country’s health. Far from the world’s urban centers, poor people suffer from
air pollution in their own homes when they cook with smoky stoves and breathe
in black carbon and other pollutants.

These benefits of cutting black carbon were already apparent before Doherty and
her colleagues published their new study; now it’s clear that cutting soot
could help not just personal health, but planetary health as well.